Pope Francis had to arrive at his welcoming reception at Guanabara Palace in
Rio de Janeiro by helicopter on Monday night as protests gathered outside
during his first foreign trip to Brazil.

The Pontiff’s plans were changed at the last minute after around 1,500 demonstrators arrived and burned an effigy tied to a lamppost. There were later clashes with police as officers tried to disperse the crowd with six detained and at least three injured.

There had been scenes of chaos as the Pope began his trip through Rio in a modest motorcade after arriving at 4pm local time. Dozens of pilgrims and well-wishers dashed to the open window of his Fiat car to greet the Pope directly.

Security experts said the Pope was left extremely vulnerable during the chaotic scenes when his car was mobbed by hundreds of Brazilians after becoming stuck in traffic in Rio.

“There was a weak point in the security of the Pope. This has to be evaluated and remedied. If there had been a hooligan among the faithful, he could have thrown a stone or something worse,” Diogenes Dantas, a colonel in the Brazilian army and an expert on security planning for major events, told the Brazilian newspaper O Globo.

Milton Corrêa da Costa, a lieutenant-colonel in the military police, agreed that Francis could easily have been attacked as people thrust their hands into the open window of his silver Fiat – a modestly-sized car that the Pope had specifically requested.

“Travelling with the window open, Pope Francis was in a vulnerable situation and could have been the victim of an attack at very close range,” he said.

Hugo Tisaka, a security consultant, said the Pope had been unnecessarily put at risk.

“Coping with crowds is very complex, even though in this case it was a group of people that was apparently not hostile.”

He said the hundreds of people who darted in and out of cars, taxes and buses to greet the Pope had also been in danger because they could have been hit by moving vehicles.

There had been “an insufficient number of agents” providing protection for the pontiff, he said.

Eva Vider, a traffic planning expert from the Federal University of Rio de Janeiro, said it was “inconceivable” that the Brazilian authorities had allowed the Pope to get boxed in by traffic within just an hour of his arrival in the country.

“The Pope’s itinerary was poorly planned,” Prof Vider said. “It’s inconceivable that the Pope or anyone else of his position, who needed a clear path, should become stuck in a traffic jam.”

But Vatican officials denied there were any concerns over security in the Pope’s first trip back to Latin America since becoming the head of the Catholic Church.

“The only change in the itinerary was at the end when leaving the presidential palace,” said Father Thomas Rosica, translating for Vatican spokesman Father Federico Lombardi.

“It was decided that the helicopter would be taken just to avoid the protests.”

While the protest - driven by a growing social movement campaigning for better public services - began peacefully, there were claims that Molotov cocktails were thrown at police, and tear gas, rubber bullets and sound bombs used in retaliation.

After meeting Brazilian president Dilma Rousseff and a number of other dignitaries, Pope Francis travelled to Sumaré, the official residence of the Archbishop of Rio, where he will stay. He has no official engagements on Tuesday.

“He enjoyed meeting everybody and greeting people. We were not at all worried about security. We were struck by the amount of enthusiasm.”

He added it was a “unique” way to enter a city and said the Pope was keen to avoid a “militarisation” of his security detail.

“I don’t want to overly dramatise the motorcade,” Fr Lombardi added through Fr Rosica. “We have full confidence in the authorities. Today was the first experience, a learning experience, and we will see what happens in the next few days.”

He also said there were no concerns about the Pope’s visit to the Aparecida shrine, where a homemade bomb was found on Sunday.

Vatican officials joked they had a “moment of fear”, though, when the Pope spent 15 minutes with the pilot in the cockpit of the plane as they landed in Rio for the Catholic Church’s World Youth Day.